1. Field of the Invention
The present invention constitutes main part of a pigment ink agitation system and specifically relates to an ink tank storing pigment ink and a printer with the ink tank.
2. Description of the Related Art
An ink jet printer is equipped with ink containers storing dye ink or pigment ink which is supplied to a printing head. In the case of using an ink container storing pigment ink, the pigment ink is left within the ink container for a long time if the printer does not print for a long time, for example. Since particles as a coloring material (coloring matter) in the components of the pigment ink (hereinafter, referred to as pigment particles) have a specific gravity greater than that of a solvent as another component of the pigment ink, the pigment particles fall down by gravity in the gravity direction within the ink container and settle on the bottom of the ink container. This causes the pigment ink stored in the ink container to have non-uniform concentration of the pigment ink and there is the possibility of inhibiting optimal quality printing with the printing head.
In order to provide a uniform distribution of pigment particles of the pigment ink in an ink containing chamber, for example, an ink jet printer is proposed in which a pair of stirring members stirring the pigment ink are swingably provided in the ink containing chamber. Each of the stirring members is composed of a thin sheet made of a metallic material having a specific gravity greater than that of the pigment ink. The stirring members are configured to swing under the inertia force due to reciprocation of a carriage with the ink container mounted thereon. Namely, the ink container is shaken hard while the carriage is moved from side to side, thus stirring the pigment ink in the ink containing chamber. The pigment particles are thus dispersed so that the concentration distribution of the pigment particles has a uniform distribution in the ink container, thus providing a uniform distribution of the pigment particles of the pigment ink in the ink containing chamber. This results in printing of good images on printing media with the printing head since distribution of the pigment particles of the pigment ink in the ink containing chamber is homogenized.
As shown in Japanese Patent Laid-open No. 2002-337360, another ink jet printer is proposed, which comprises a heater provided to a carriage to heat the bottom of a cartridge for the purpose of stirring ink within the cartridge without complicating the structure of the cartridge. Heating the ink near the bottom of the ink chamber with the heater causes convection of the ink within the ink chamber. The ink within the ink chamber is thus stirred.
Furthermore, a structure for the purpose of stirring magnetic ink in an ink chamber of a cartridge has been proposed as shown in Japanese Patent Laid-open No. 2002-337360, the structure in which magnetic particles in the ink chamber are attracted by magnets provided at right and left ends. That is, when the carriage with the cartridge mounted thereon moves to the left end, the magnetic particles in the ink chamber are attracted by the magnet provided at the left end. On the one hand, when the carriage moves to the right end, the magnetic particles in the ink chamber are attracted by the magnet provided at the right end. Therefore, with such a structure, the magnetic ink in the ink chamber is stirred.
As shown in Japanese Patent Laid-open No. H08-258281 (1996), an ink ejection device has been proposed, in which a rod-like adsorption electrode, a large planer electrode, and an alternating voltage application unit applying alternating current voltage to the electrodes are provided in an ink container. With such a structure, dusts and the like suspended in the ink container, which adversely affect the quality of an image formed on a printing medium and a printing operation of the printing head, are adsorbed and removed.
In such a structure, when alternating voltage is applied between the pair of electrodes having different shapes, the rod-like adsorption electrode adsorbs dusts suspended in the ink and the like. Accordingly, large dusts and the like which will clog the ink ejection portion are removed from the ink, avoiding clogging of an ink filter.